A large number of people with diabetes use some form of daily insulin therapy to maintain close control of their glucose levels. Currently, there are two principal modes of daily insulin therapy. The first mode includes syringes and insulin pens. These devices are simple to use and are relatively low in cost, but they require a needle stick at each injection, typically three to four times per day. The second mode includes infusion pump therapy, which entails the use of an insulin pump. Although the initial cost of the pump can be significant, the overwhelming majority of patients who have used pumps prefer to remain with pumps. This is because infusion pumps, although more complex than syringes and pens, offer the advantages of continuous infusion of insulin, precision dosing, and programmable delivery schedules. This results in closer blood glucose control, which can result in improved health outcomes for the patients.
The use of an infusion pump requires the use of a disposable component, typically referred to as an infusion set, line set, extension set or pump set, which conveys the insulin from a reservoir within the pump into the skin of the user. An infusion set typically consists of a pump connector, a length of tubing, and a hub or base from which an infusion cannula (i.e., an infusion needle or a flexible catheter) extends. The hub or base has an adhesive which retains the base on the skin surface during use, which may be applied to the skin manually or with the aid of a manual or automatic insertion device.
However, there are problems associated with the delivery of insulin by such devices during sleep. During sleep, people tend to move and such movement can result in accidental disconnection of the line set, removal of the infusion cannula, or tugging of the line set that can result in tunneling or leakage at the infusion site. Tunneling can occur when an infusion cannula that has been inserted into a user leaks insulin along the outer walls of the tubing of the infusion cannula, back to the skin, usually after a large bolus. Since many components are attached to the user of such devices, this further adds to the level of discomfort to the user, reducing the comfort level of the user during periods of rest when discomfort should be minimized.
In addition, during periods of rest, such as during sleep at night, a diabetic patient is subject to different conditions than during times of activity, such as during the day. During sleep time, since the patient does not eat, the level of insulin required (basal dose) is nearly constant and substantially reduced as compared to the insulin requirement (bolus dose) at meal times or during active times during the day.
Accordingly, a need exists for a device that can deliver basal dose medication to the subcutaneous or intradermal skin layer, during times of rest, while maintaining a high degree of comfort to the user by eliminating unnecessary components that contribute to user discomfort.